In image-guided surgery (IGS) a medical practitioner uses instruments that are tracked in real time so that positions and/or orientations of the instruments may be presented on images of a subject's anatomy during a surgical procedure. In some cases both the tracking and the imaging of the subject's anatomy may be implemented by one modality, such as fluoroscopy. However, because fluoroscopy uses ionizing radiation, its use should be minimized. Consequently in many scenarios an image of the subject is prepared in one modality, such as magnetic resonance imaging (MRI) or computerized tomography (CT) fluoroscopy, and the instrument tracking uses a different modality, such as electromagnetic tracking.
U.S. Pat. No. 5,335,173 describes a medical diagnosis image display method comprising the steps of transforming respective three-dimensional image information on a skull of a subject to be examined and diagnosed and skin covering the outer surface of the skull.
U.S. Pat. No. 6,081,739 describes a conventional digital panoramic radiographic unit, which includes sonic or optical three dimensional scanning detector and a color video detector so that when the panoramic x-ray data is obtained, three dimensional contour of the surface of the subject's skin and the outward visual appearance of the subject's skin are also obtained as correlated data sets.
U.S. Pat. No. 5,813,984 describes a method and device for generating a forensic skull and soft tissue database used for the on-line facial reconstruction of victims and age progression portrait rendering of missing children through utilization of advance diagnostic radiologic modalities.
European Patent EP0581704B1 describes a method for determining the position of an organ of a subject with respect to at least two image-forming devices.
U.S. Pat. No. 6,524,250 describes a device that can be easily used by surgeons to measure and monitor changes before, during, and after a liposuction procedure and assist in producing symmetrical body contours.